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Dynamic Analysis of an Exoskeletal System to Assist a Paraplegic Motion

Selk Ghafari, Ali | 2010

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 40248 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Meghdari, Ali; Vossoughi, Gholam Reza
  7. Abstract:
  8. This research focuses on the dynamic analysis of an exoskeletal system to assist a paraplegic motion. Research in powered human exoskeletons began in the late 1960s, almost in parallel between the numbers of research groups for different applications. The main challenges for the recent work in exoskeletons were focused on the design and demonstration of an initial prototype. To this point, the reported advantages of the autonomous exoskeleton systems are largely anecdotal. Indeed, there is a marked lack of published quantitative performance results for exoskeleton devices that reportedly improve human locomotion. Considering this, there are many design challenges remained that may lead to poor exoskeleton performance, such as misalignment of joints between operator and exoskeleton structure, kinematic constraints from attachments such as harnesses and cuffs, added forces to the operator that resist motion. All of these problems are very difficult to address, however there is much opportunity for fundamental studies addressing these challenges. Software for musculoskeletal modeling and simulation is a powerful tool to facilitate the appropriate criterions for an anthropometric design of the exoskeleton structure. This research was conducted to investigate the dynamic interactions between the musculoskeletal system and assistive systems in order to promote our knowledge the field of design, prototyping and simulation of exoskeletal systems. A biomechanical framework was generated with the aim of employing a block-oriented structure of Simulink integrated with the various toolboxes of MATLAB software to provide a simulation study of the musculoskeletal system in various conditions. In addition the vector bond graph approach as a modeling tool for handling multi-energy domain systems was employed to derive the mathematical model of the system. For this purpose, a three-dimensional musculoskeletal system including eighteen musculotendon actuators per leg was developed. An extensive biomechanical analysis were carried out to identify the lower extremity muscles function during various activities, such as level walking, stair ascent and descent, and load carrying. In the next stage, based on the energetic analysis an anthropometric exoskeletal system was designed to provide motion assist. In the final stage, an impedance feedback control system was proposed to provide a stable gait for paraplegics. This research provides a biomechanical framework to design and dynamic analysis of the exoskeletal systems and orthosis in virtual environment
  9. Keywords:
  10. Dynamic Modeling ; Impedance Control ; Paraplegic Patienst ; Exoskeletal System ; Vectorial Bond Graph

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